Overload signatures causes `[no-redeclare]`error from eslint

[chancancode]

Haven't had a chance to test this in an isolated reproduction, so I'm not 100% sure if this is a problem with the eslint plugin or the eslint parser.

export function foo(arg: string): string;
export function foo(arg: number): number;
export function foo(arg: string | number): string | number {
  throw "not implemented";
}

This works fine with a .ts extension, but if you rename it to .gts extension it gives error 'foo' is already defined no-redeclare.

• no-redeclare

Seems like possibly a parser issue, but AFAIK the parser largely delegates to the eslint TS parser, and I am using the ember-eslint-parser globally (for js/ts/gjs/gts files) since it is supposed to work just fine (and did here) on regular non-glimmerized files. I suppose it's possible that the something went slightly wrong in the AST translation.

[patricklx]

It's probably a config issue. no-redeclare should be disabled for gts.
The typescript eslint rule should be used

[chancancode]

hm, you are right, that was the intention of the config, I'll dig into why it didn't get applied here, thanks! I'll re-open in the right repository if I found an issue.

[patricklx]

It should come from here https://github.com/ember-cli/eslint-plugin-ember/blob/ea0e3802b9971884eab5092e07730e4a0b04d9de/lib/config/recommended-gts.js#L6

[chancancode]

Yea, I'm still looking into it, from what I gathered in the debug logs, that should be happening –

1. first eslint:recommended sets it to "error"
2. then @typescript-eslint/eslint-recommended overrides it to "off"
3. then @typescript-eslint/recommended-type-checked overrides it to "off" once more

It's probably worth mentioning that while I do see that plugin:ember/recommended-gts is being loaded/extended for this file, I don't see that it tried to override no-redeclare etc, because I'm using legacy config, and the legacy config in the plugin seems to only add "ember/template-no-let-reference": "error" without any of the other stuff you showed in the flat config version:

• https://github.com/ember-cli/eslint-plugin-ember/blob/master/lib/config-legacy/recommended-gts.js
• https://github.com/ember-cli/eslint-plugin-ember/blob/master/lib/recommended-rules-gts.js

Not sure if I'm just misunderstanding how that works or if those configs got out of sync.

In any case, there is clearly something else going on here, since even without that, the overrides from typescript-eslint should have been sufficient. So I'll go back to figuring out what's up with that. But thought I should update you on this other discrepancy in case it's unexpected for you.

[chancancode]

@patricklx I think I found the issue. The typescript-eslint legacy config is scoped to a glob of *.ts (among other things, but not including *.gts obviously), so it has no effect. (typescript-eslint/typescript-eslint#8607, heh)

So that leaves us with the only thing that is supposed to turn the rule off is plugin:ember/recommended-gts legacy config, but that also doesn't do it, as I pointed out in the previous comment, which I suspect is unintended.

I suppose I should just invest some time in switching to the flat config and I'll have an easier time managing all of these merging problems, but in the meantime, the README does indicate we support the legacy config, and from what I can tell, it's not doing what we intended right now.

In any case, that would be an issue with the eslint plugin, not the parser. If this sounds like a problem to you I'm happy to open the issue there.

[chancancode]

Moved to ember-cli/eslint-plugin-ember#2262